Thanks for the demultiplexer idea, Not sure that you need the diodes , my thoughts run like this: assume it is a 7 x 16 crosspoint array and they are A thru G for the the 7 lines and 1 thru 16 for the 16 lines. If A is connected to 1 and A is also connected to 2. Then if you put a hi on the pinin that is A and read out the 1 thru 16 lines then you would get a Hi on pinin 1 and also pinin 2 , this then says that both A1 and A2 are closed. What am I missing when you say I need diodes?